The invention relates to a winch comprising a substantially cylindrical housing, rotatably disposed around a central shaft, which housing comprises, at the top thereof, a flange and has a central portion of a diameter smaller than the diameter of the flange and the diameter of the bottom housing portion.
Such a winch, constructed as a self-tailing winch, is disclosed in Dutch patent application 8202198. In a self-tailing winch, the flange becomes thinner toward the circumference and a plate is mounted on the top side of the flange, which plate also becomes thinner toward the circumference and has a diameter equal to that of the flange. Thus, between the flange and the plate a V-shaped groove is present for receiving the line or sheet, directed to a specific shape of the tooth-shaped raised portions which are usually provided on the surfaces, facing each other, of the flange and the plate and which are intended to hold a tight fit on the line or sheet to be wound onto the winch in the V-shaped groove. For this type of winch, as well as for winches of the non-self-tailing type, it is conventional to roughen the outer surface of the central portion of the housing so as to prevent the line or sheet from slipping over the housing surface. The roughness of the surface is in the order of magnitude of 100-150 grains/cm.sup.2 and is obtained through a jetting operation with a stainless-steel jetting means. Such slipping of the line has a very adverse effect on the proper functioning of the winch and consequently, experts regard the rough surface of the central portion as strictly necessary. A drawback of the roughened surface, however, is an extra wear of the line portion which is wound around that surface and in particular of the portion which, coming from the sail, first contacts the rough surface. However, this wear has heretofore been considered unavoidable.